Apparatus for plugging cased petroleum production wells

ABSTRACT

An umbrella unit which is screwed to an actuating tool and lowered into the production tubing of an oil well by means of a wire line is fitted with a set of upwardly directed and a set of downwardly directed spring-actuated knives which are outwardly and radially displaceable within the well casing so as to lock said umbrella against the casing wall in the required plugging position, the umbrella proper being then caused to open out radially and filled with gravel or like material. A spoon comprising a reservoir tube filled at the wellhead with cement grout is lowered by means of a wire line, the cement grout being discharged through bottom openings by means of a glass window which is broken by means of a striker piece upon impact of the bottom of the spoon on the gravel.

Unite States Patent inventors Appl. No. Filed Patented Assignee Priority Guy de Lajarte Toulouse;

Jacques de Saint Palais, Saint Gaudens, both of France Feb. 16, 1970 Nov. 30, 1971 Entreprise de Recherches et d'Activltes Petrolieres (Elf) Paris, France Feb. 26, 1969 France APPARATUS FOR PLUGGING CASED PETROLEUM PRODUCTION WELLS 1 Claim, 4 Drawing Figs.

U.S. Cl [66/125, 166/202, 166/134 Int. Cl ..E21b23/06, E2lb 33/126 Fieldoisearch 166/118, 125,135,136, 202

Primary ExaminerDavid H. Brown Attorney-Cameron, Kerkam & Sutton ABSTRACT: An umbrella unit which is screwed to an actuating tool and lowered into the production tubing of an oil well by means ofa wire line is APPARATUS FOR PLUGGING CASED PETROLEUM PRODUCTION WELLS This invention relates to an apparatus for plugging cased petroleum production wells.

It is known that, in general principle, a producing well which usually extends to a depth of several thousand meters from the wellhead to the oil pool or reservoir is lined from ground level down to the vicinity of the reservoir with a casing string consisting of tube lengths or so-called joints which are screwed together in end-toend relation and anchored to the wall of the well bore by means of Portland cement. in the case of a very tight reservoir formation such as limestone, the casing is stopped above the formation; in the most frequent case of an unconsolidated formation such as sand and sandstone, protection of the producing stratum or strata is ensured by means of a casing which is cemented and then perforated in order to obtain a flow of reservoir fluids into the well; consideration will be given hereinafter only to the practice last mentioned.

A production tube or so-called tubing string is run into the hole within the casing and coaxially with this latter; the tubing extends downwards from the ground level to a slightly smaller depth than the casing (the lower end or tubing shoe is always placed at a level slightly above the producing horizon). This production string consists of an assembly of steel tube lengths which are screwed together.

A problem which frequently arises is the need to plug a production well because it can no longer be exploited economically or because it is desired either to abandon the bottom part of the reservoir when the water production attains an unacceptable level.

Numerous methods have been devised for laying-in plugs in production wells; the conventional methods consist in placing a mechanical plug or cement plug but in all cases entail preliminary dismantling of the well equipment. Other methods avoid dismantling of equipment by means of a device referred to as an umbrella which is run into the well under pressure. The umbrella is actuated from the wellhead and caused to extend radially outwards so as to grip the wall of the production tubing; an instrument known as a spoon is then lowered into the well and discharges onto the umbrella materials which are intended to form the plug (cement or resin).

As a rule, the umbrella and the spoon are operated from the ground by means of a cable which controls all the operations electrically and in particular initiates the release of the instruments by electric triggering.

Electric triggering from the ground represents an excellent technical solution since it ensures complete safety of the instruments both during their downward and upward motion as well as the anchoring of said instruments at a precisely determined depth.

However, the various known methods of electrical positioning have the disadvantage of entailing heavy capital expenditure by reason of the cost of tools as well as the cost of each positioning operation. Moreover, the size and extent of the means employed at the wellhead (specially equipped truck or cabin) makes this operation unattractive on an ocean platform.

In another plugging process which is also known, the umbrella and the spoon are lowered and positioned, not electrically, but mechanically by means of a cable or wire line without initial dismantling of the well and simply by insertion into the production tubing through a tubular lock chamber which is attached to the Christmas tree.

Although the process which has just been described is more simple and economical than those mentioned earlier, it is still not possible to bring tools to the surface in the event of any accidental stoppage near the bottom during downward motion of the tools within the production tubing,

The present invention relates to a plugging apparatus which is also actuated mechanically by means ofa cable or wire line and introduced through a lock chamber under pressure into the production tubing without entailing the need for dismantling of the well but which has the further advantage of permitting upward withdrawal to ground level at any moment as long as said apparatus has not passed below the bottom extremity or shoe of the production tubing. A further advantage of the apparatus lies in the fact that it permits of more accurate positioning than the mechanical plugging device of the prior art by reason of the novel design of its anchoring knives, of its device for setting the umbrella in position and of its spoon.

More specifically, this invention is concerned with an apparatus for plugging tube-lined petroleum production wells, said apparatus being essentially characterized in that it comprises on the one hand an umbrella which is associated with its actuating tool by screwing, said umbrella being provided with a central rod, a bottom portion or shoe adapted to carry a lower set of knives upwardly directed to the top of said rod and a downwardly directed upper set of knives, said knives being fitted with springs which tend to displace them radially outwards from said shoe, an umbrella proper formed of blades each attached to a flexible strip which tends to displace said blade radially outwards from the central rod and a sleeve adapted to cover the umbrella proper and terminating in a threaded portion through which extends the upper extremity of the central rod and said actuating tool being provided with a cylinder whose hollow bottom portion is screwed on the umbrella and contains a cap rigidly fixed to said rod by means of a shearable locking pin and to said bottom portion by means of at least two balls and whose top portion which is attachable to an operating cable is adapted to carry a set of spring blades which are capable of moving toward said top portion under the action of a compressive force and which are secured at the lower end thereof to a sleeve which covers said balls within the production tubing and which released said balls under the action of extension of said spring blades relative to said top portion and, on the other hand, a spoon which serves to discharge sealing materials, said spoon being designed to comprise a reservoir tube whose top portion is attachable to an operating cable and has a window for the introduction of sealing materials and whose bottom portion has a smaller diameter than that of said top portion and is fitted internally with a safety glass and externally with a set of spring blades which are capable of moving towards said bottom portion under the action of a compressive force and which are secured at the lower end thereof to a sleeve which is capable of slight displacement along said reservoir tube, the lower extremity of said reservoir tube being adapted to carry a container provided with windows for the discharge of sealing materials.

According to one form of construction, said container is a shoe which encloses a striker piece, said shoe in the inoperative state thereof being rigidly fixed to the reservoir tube by means of a locking device which is released from said shoe under the action of extension of said spring blades with respect to the reservoir tube, said shoe being capable of sliding along the reservoir tube over a short distance under the action of an irripact and of breaking said safety glass by means of its striker piece.

Further properties and advantages of the present invention will become apparent from the following description which is given by way of explanation without any limitation being implied and relates to one form of construction of the umbrella and actuating tool as well as to one form of construction of the spoon for discharging sealing materials.

Reference is made to the accompanying drawings which are views in elevation and in axial longitudinal cross section, and in which:

FIG. 1 illustrates an umbrella in accordance with the invention, the umbrella proper being in the withdrawn position;

FIG. 2 illustrates the umbrella-actuating tool which is screwed on the top portion of the umbrella;

FlG. 3 illustrates the umbrella of FIG. 1 which is anchored to the casing of the production well, the umbrella proper being in the radially extended position;

FIG. 4 illustrates a first form of construction of the spoon.

The umbrella unit as shown in FIG. 1 comprises a central rod 1 and a bottom portion or shoe 2 fitted with four upwardly directed bottom knives 3 (only two of which are visible in the figure) and four downwardly directed top knives 4 and a catch 5 which serves as a stop for the sleeve 6 of the umbrella unit, the eight knives being of identical design.

Springs 7 formed of piano wire are attached to the different knives 3 and 4 and tend to displace these latter radially outwards.

The umbrella unit also comprises the umbrella 8 as constituted by blades 9 which are formed of metallic foil. Each blade tends to open by virtue of a rib 10 of spring steel (as shown in FIG. 3). Said ribs are joined together by means of a cylindrical base 11 formed of lead and cast around a guide tube 12.

Leak tightness of the base of the umbrella 8 proper is ensured by means of block 13 formed, for example, of elastomer foam which affords resistance to hydrocarbons.

Finally the sleeve 6 tenninates in a threaded portion 14 through which extends the upper extremity of the central rod 1.

All the components of the umbrella unit are mounted at works, the sleeve 6 being locked in position by means of a movable safety lug 15 which couples said sleeve to the shoe 2.

The tool which serves to actuate the umbrella of FIG. 1 comprises a cylinder 16 (shown in FIG. 2), the lower half of which is hollow and provided with an internal screw thread. Said tool is screwed on thethreaded portion 14 of the umbrella sleeve 6 after successively passing over the top portion of the central rod 1 which is housed within the cylinder 16 a guide tube 17, a spring I8 under light compression and a cylindrical cap I9 which is rigidly fixed to the rod 1 by means of a shearable locking pin 20 formed of brass, for example.

Screwing of the actuating tool on the threaded end 14 has the effect of compressing a spring 21 which as previously been inserted in the cavity 22 of said tool. The umbrella is then retained solely by the safety lug 15.

A set of two spring blades 23 referred to as a lantern is passed over the top portion of the cylinder 16 of the actuating tool. Said spring blades are attached at their upper extremities to a sleeve 24 which is rotatably fitted in an annular groove 25 of the cylinder 16 and at their lower extremities to a sleeve 26 which is capable of free displacement over a distance of a few centimeters.

A groove 27 formed in the cylindrical cap 19 is located opposite to two holes of the cylindrical wall 16. Two steel balls 28 are placed in said holes, thereby rigidly coupling the umbrella unit with the actuating tool.

The upper extremity of the tool is provided with a threaded end 29 for screwing the cable or wire line which is employed for lowering the umbrella unit into the well.

The operation of the assembly which consists of umbrella unit and actuating tool is carried out as follows:

When the cable line has been connected by screwing to the threaded end 29, a gage having the same dimensions as the umbrella unit is first screwed to the lower end of the actuating tool in the place of said umbrella unit, the assembly being lowered into the production tubing in order to check freedom of passage within this latter.

When this checking operation has been completed. the gage is replaced by the umbrella unit and the assembly is inserted in the lock chamber which is located at the surface.

The spring blades 23 being thus compressed, the bottom sleeve 26 is thrust downwards so as to cover the balls 28.

When the tool and umbrella assembly has passed almost completely within the lock chamber, the safety lug 15 is withdrawn and the umbrella unit is accordingly coupled to its actuating tool solely by means of the balls 28 and the shearing pin 20. The lock chamber is then connected to the tubing head or Christmas tree and brought to the same pressure as the production tubing; the valves of the Christmas tree are then opened and the complete assembly is lowered into the tubing.

When the two blades 23 reach a point below the lower end or shoe of the production tubing, said blades open out and the bottom sleeve 26 moves upwards, thereby releasing the balls 28 which are ejected as a result of expansion of the spring 21.

Under the action of said spring 21, the cylindrical cap 19 and the umbrella unit are thrust downwards; in consequence, the bottom knives 3 are released and then thrust outwards by their springs 7 against the casing 30 of the production well (as shown in FIG. 3). The umbrella is then prevented from moving upwards by the knives but at this stage is still permitted to move downwards.

The top knives 4 are held in the closed position by the sleeve 6 of the umbrella which is retained by the spring 18.

At the level at which the umbrella unit is anchored within the well bore, an upward tractive force is applied to the actuating tool: the bottom knives 3 prevent the tool from moving upwards; the top knives 4 and the stop catch 5 are unmasked and the knives 4 are thrust outwards against the well casing 30. The umbrella unit is thus prevented from moving downwards by the knives and at this stage is no longer permitted to move either in the upward or downward direction.

The spring 18 is compressed until cap comes into abutting contact with the guide tube 17.

The tension applied to said tool the sleeve 6 to move downwards and closing the jar of the wire line.

By subjecting said jar to a few jerks, the pin 20 is sheared, with the result that both the actuating tool and the sleeve 6 6 can be upwardly withdrawn and that the umbrella proper 8 can open out in a movement of radial extension and thus be abuttingly applied against the well casing 30.

There then remains within the well bore only the shoe 2, the anchoring knives 3 and 4, the stop catch 5, the extended umbrella 8 and the central rod 1 (as shown in FIG. 3).

After it has been raised to the surface, the sleeve 6 is either discarded or used again.

Since the umbrella proper is anchored against the wall of the casing 30, it only remains to seal the well, this operation being carried out with the aid ofa spoon.

As shown in FIG. 4, said spoon essentially comprises a reservoir tube 31, a lantern 32 comprising two spring blades and a container or shoe 33.

The tube 31, the lower portion of which is of smaller diameter, is sealed at the bottom end by means of a glass disc 34 which is held in its recess by a clamp between two sealing rings.

The upper portion of the tube 31 is provided with a window 35 for the introduction of cement grout and terminates in a screw thread 36 for the attachment of the wire line.

The lantern 32, which is identical with the lantern of the umbrella-actuating tool, is passed over the lower portion of the tube 31, the top sleeve 37 of said lantern being locked in position and secured against rotation. The bottom sleeve 38 of the lantern locks the shoe 33 in position by means of two safety lugs 39 during manipulation of the spoon within the production tubing.

The shoe 33 serves to protect the glass disc 34 during the downward travel of the spoon within the production tubing by means of the two lugs 39 and within the casing 30 by means of a spring 40.

The glass disc 34 is caused to break under the action of a striker piece 41 as the shoe of the spoon drops onto the gravel which has previously been discharged onto the extended umbrella 8.

The cement grout with which the tube 31 has been filled is then permitted to flow through wide openings 42.

The shoe 33 is adapted to slide within the bottom portion of the spoon by means of a chamfered lug attached to a blade spring, thereby permitting rapid replacement of the glass disc.

The operation of the spoon is as follows:

At the wellhead, the glass disc 34 is placed inside its recess and the spoon is filled with cement grout through the opening 35.

is released, thereby causing again onto the stop catch 5 The lantern 32 and the shoe 33 are placed in position and the complete assembly is screwed to the wire line by means of the threaded end 36.

The assembly is passed into the lock chamber and then run inside the production tubing.

At this stage, the bottom sleeve 38 of the lantern 32 covers the safety lugs 39 of the shoe.

Said lugs 39 are released when they have passed below the production tubing. The glass disc 34 is then protected by the spring 40.

When the spoon strikes the gravel with which the umbrella has been covered, the spring 40 is compressed and the striker piece 41 fractures the glass disc 34. The cement grout then flows under gravity through the openings 42, whereupon the spoon is raised again to ground level.

In the operations described in the foregoing, it has been as sumed that round gravel or glass beads have been discharged onto the extended umbrella. Should it be found undesirable to pour said gravel into the casing under the action of gravity from ground level, the gravel can be discharged into the well by means of the above-mentioned spoon to which a pot of lightweight sheet metal (not illustrated) is fitted in place of the shoe 33.

Once the gravel has been discharged, the pot is abandoned on the mass of gravel.

It will be apparent that this invention has been described in the foregoing solely by way of explanation without any limitation being implied and that any detail modification may accordingly be contemplated without thereby departing from its scope.

ln particular, the design of the spoon can be other than that which has just been described. For example, if the spoon is intended to discharge a liquid product at a predetermined level of the production tubing, the lantern 32 is replaced by locking pins and the safety lugs 39 are dispensed with. An O-ring seal prevents the passage of liquid between the shoe and the spoon.

What we claim is:

1. An apparatus for plugging tube-lined petroleum production wells, wherein said apparatus essentially comprises an umbrella unit associated with its operating tool by screwing, said umbrella unit being provided with a central rod, a bottom portion carrying a lower set of knives upwardly directed to the top of said rod and a downwardly directed upper set of knives, said knives having springs to displace them radially outwards from said shoe, an umbrella proper formed of blades each attached to a flexible strip to displace said blade radially out wards from the central rod and a sleeve covering the umbrella proper and terminating in a threaded portion through which extends the upper extremity of the central rod and said operating tool being provided with a cylinder, a hollow bottom portion for said cylinder screwed on the umbrella unit and containing a cap rigidly fixed to said rod by a shearable locking pin and to said bottom portion by at least two balls and a top portion for said cylinder attachable to an operating cable carrying a set of spring blades moving towards said top portion under the action of a compressive force and secured at the lower end thereof to a sleeve covering said balls within the production tubing and releasing said balls under the action of extension of said spring blades relative to said top portion. 

1. An apparatus for plugging tube-lined petroleum production wells, wherein said apparatus essentially comprises an umbrella unit associated with its operating tool by screwing, said umbrella unit Being provided with a central rod, a bottom portion carrying a lower set of knives upwardly directed to the top of said rod and a downwardly directed upper set of knives, said knives having springs to displace them radially outwards from said shoe, an umbrella proper formed of blades each attached to a flexible strip to displace said blade radially outwards from the central rod and a sleeve covering the umbrella proper and terminating in a threaded portion through which extends the upper extremity of the central rod and said operating tool being provided with a cylinder, a hollow bottom portion for said cylinder screwed on the umbrella unit and containing a cap rigidly fixed to said rod by a shearable locking pin and to said bottom portion by at least two balls and a top portion for said cylinder attachable to an operating cable carrying a set of spring blades moving towards said top portion under the action of a compressive force and secured at the lower end thereof to a sleeve covering said balls within the production tubing and releasing said balls under the action of extension of said spring blades relative to said top portion. 